Engineering Commons^™

Endothelialization Using Protein Substrates And Hydrogels For Aortic Valve Applications, Elizabeth A. Fontaine

All Theses

Aortic valve disease is currently the leading cause of cardiovascular morbidity in the United States.1 In 2003, approximately 290,000 patients required heart valve replacement and that number is estimated to continue to rise as the average age of the population continues to increase.2 However, the current valve replacement options have multiple limitations. Tissue engineering hopes to address these shortcomings by providing a viable valve that more closely mimics the native valve, structurally and functionally.3 An ideal valve replacement should contain endothelial and interstitial cells, with the ability to remodel the extra-cellular matrix. While tissue-engineered heart valves are not uncommon in …

Cloud-Based Strategies For Robust Connectivity And Efficient Transmission In Vehicular Networks, Ke Xu

All Dissertations

Leveraging multiple wireless technologies and radio access networks, vehicles on the move have the potential to get ubiquitous broadband Internet connectivity. Many studies have put lots of efforts on vehicle-to-vehicle networks for relaying strategies, popular content distribution, etc. However, in dominant infrastructure-based vehicular networks, supporting continuous and fast data transfer for today's prevalent services, e.g. video streaming, for vehicles anytime and anywhere is still a difficult research problem. By looking into such problem, impacts such as intermittent connectivity, dynamic network topology, fluctuating signal coverage, and inefficient transmissions, all result from two root causes in vehicular network- mobility and limited infrastructure …

Capillary Channel Polymer Fiber-Based Scaffolds For Neural Regeneration, Atanu Sen

All Dissertations

Over 50 million Americans are affected by ailments to the central nervous system (CNS) and it impacts the American economy over $400 billion a year. The number of people in the United States who have spinal cord injury (SCI) has been estimated to be approximately 276,000 persons as of 2014 with a range from 240,000 to 337,000 persons. The annual incidence of SCI, not including those who die at the scene of the accident is approximately 12,500 new cases each year. Due to the limited regenerative capacity of the adult CNS and lack of clinically effective therapies, these conditions commonly …

Hazard Quantification And Loss Estimation For Combined Hurricane Wind And Flood, Bin Pei

All Dissertations

This research work focused on developing and evaluating the methodologies proposed for hazard quantification and loss estimation of the combined hurricane wind and flood. The overall research was divided into three studies. A methodology to quantify the joint occurrence probability of hurricane wind and flood was first introduced in Study I. A procedure to select ensembles of hazard-consistent full-track hurricane scenarios (i.e. with similar return periods) was proposed next in Study II. Finally in Study III, a new hurricane mitigation framework was developed using the agent-based modeling (ABM) technology to evaluate the effectiveness of incentive programs under both hurricane wind …

Linear Programming Methods For Identifying Solvable Cases Of The Quadratic Assignment Problem, Lucas Waddell

All Dissertations

This research effort is concerned with identifying and characterizing families of polynomially solvable instances of the celebrated NP-hard quadratic assignment problem (qap). The approach is novel in that it uses polyhedral methods based on an equivalent mixed 0-1 linear reformulation of the problem. The continuous relaxation of this mixed 0-1 form yields a feasible region having extreme points that are both binary and fractional. The solvable instances of concern essentially possess objective function structures that ensure a binary extreme point must be optimal, so that the linear program solves the qap. The ultimate contribution of this work is the unification …

Lateral Control Of A Vehicle Platoon, Samuel A. Mitchell

Undergraduate Honors Capstone Projects

Multiple lateral control systems are analyzed for use in a vehicle platoon system. In order to ensure the safety of the vehicle platoon, the system must operate under three constraints: (1) accurate path following, (2) string stability, and (3) functionality in the presence of noise. Computer simulations are employed to analyze candidates according to the safety requirements. Actual vehicle kinematics and nonlinearities - limits on turn radius, velocity, and acceleration - are included in this analysis.

Successful control system candidates are implemented in a platoon of five differential-steer vehicles. The sensing and communication requirements of the control system are discussed. …

Burnout, No, And Flame Characterization From An Oxygen-Enriched Biomass Flame, Steven Andrew Owen

Theses and Dissertations

Concern for the environment and a need for more efficient energy generation have sparked a growing interest throughout the world in renewable fuels. In order to reduce emissions that negatively contribute to global warming, especially CO2, enormous efforts are being invested in technologies to reduce our impact on the environment. Biomass is an option that is considered CO2 friendly due to the consumption of CO2 upon growth. Co-firing biomass with coal offers economic advantages because of reduced capital costs as well as other positive impacts, such as NOx and SOx emission reductions. However, due to the large average particle size …

Active Control Of The Human Voice From A Sphere, Monty J. Anderson

Theses and Dissertations

This work investigates the application of active noise control (ANC) to speech. ANC has had success reducing tonal noise. In this work, that success was extended to noise that is not completely tonal but has some tonal elements such as speech. Limitations such as causality were established on the active control of human speech. An optimal configuration for control actuators was developed for a sphere using a genetic algorithm. The optimal error sensor location was found from exploring the nulls associated with the magnitude of the radiated pressure with reference to the primary pressure field. Both numerically predicted and experimentally …

Modeling And Simulation Of Radiation From Electronic Transitions In Hypersonic Atmospheric Reentry Flow, Curtis Scholz

Doctoral Dissertations and Master's Theses

A capability for higher accuracy heat transfer modeling in CFD for hypersonic re-entry flows, via inclusion of thermal radiation, is sought. With temperatures reaching tens of thousands of degrees, radiation is known to be significant to chemical reaction rates and thermal boundary layer development, hence surface heat transfer and thermal ablation both to the heat shield and the backshell region of re-entry vehicles. Two current NASA solicitations seek such an improved capability relative to the Mars and Earth entry problems, as uncertainty typically leads to overdesign and excess weight. The present research develops a first physics-based “building block,” which computes …

Supersonic Retro-Propulsion Computational Fluid Dynamics Analysis Applied To Future Mars Mission, Margarita Nataly Brandt

Doctoral Dissertations and Master's Theses

Supersonic Retro-Propulsion is one of the most promising emerging technologies being considered by NASA for use in future Mars missions. This new form of Entry Descent Landing has the potential to help increase the allowable payload mass currently constraining many science instruments and operations. Computational Fluid Dynamics was used to show the feasibility of supersonic retro - propulsion in Mars atmospheric conditions. The results presented show the SRP will be able to perform satisfactory using the same conditions that the Curiosity Rover was exposed to during its landing sequence. The plume expansion was analyzed for various cases, moving from free …

Aerodynamic And Structural Design Of A Winglet For Enhanced Performance Of A Business Jet, Nicolas El Haddad

Doctoral Dissertations and Master's Theses

The preliminary design of a winglet to improve the range and fuel burn of the Falcon 10 business jet is presented. Twelve candidate geometries were studied varying the cant angle and the span. The configuration offering the best compromise between induced drag reduction, profile drag increase and weight increase due to the winglet structure and necessary wing structural reinforcement was selected. More refined analysis was performed for that winglet with Reynolds averaged Navier-Stokes computational fluid dynamics and finite element analysis. Range and fuel burn were finally calculated for a typical mission using these refined results. The selected winglet, with a …

Attitude Determination & Control System Design And Implementation For A 6u Cubesat Proximity Operations Mission, Francisco J. Franquiz

Doctoral Dissertations and Master's Theses

The purpose of this work is to discuss the attitude determination and control system (ADCS) design process and implementation for a 12 kg, 6U (36.6 cm x 23.9 cm x 27.97 cm) CubeSat class nano-satellite. The design is based on the requirements and capabilities of the Application for Resident Space Object Proximity Analysis and IMAging (ARAPAIMA) proximity operations mission. The satellite is equipped with a cold gas propulsion system capable of exerting 2.5 mN m torques in both directions about each body axis. The attitude sensors include an angular rate gyro and star tracker (STR), supplemented by the payload optical …

Design And Manufacturing Of A Mecanum Wheel For The Magnetic Climbing Robot, Shruti Deepak Kamdar

Doctoral Dissertations and Master's Theses

An AndyMark Mecanum Wheel has been re-designed for better performance and utilization by Helical Robotics. Mecanum Wheel is a complex "Omni-Directional" wheel that currently contains several drawbacks. The drawbacks include design, usage of hobby grade material, bumps in rollers, etc. A comprehensive design of the Mecanum wheel is being presented using Computer Aid Software, CAD and analysis tools, such as Finite Element Analysis, FEA. The different concepts were hand sketched using various parameters and then implemented in a CAD software-- CATIA. The Mecanum Wheel's feasibility was thoroughly studied through ANSYS software. Load analysis was performed using various materials and several …

Reducing Radio Frequency Susceptibilities In Commercial-Off-The-Shelf Camera Equipment For Use In Electromagnetic Compatibility Testing, Kevin Mainini

Electronic Theses and Dissertations

The Technical Testing and Analysis Center (TTAC) Group at Oak Ridge National Laboratory performs electromagnetic compatibility testing on various radiation detection units. These tests require remote viewing of the equipment’s display to monitor its compliance with national and international standards. The Commercial-Off-the-Shelf (COTS) camera equipment that is used to monitor the displays exhibits radio frequency susceptibilities causing issues when determining the actual susceptibilities of the device under test. In order to mitigate this issue, a COTS camera was placed in two common test positions and cycled through three angled orientations with various radio frequency shielding methods applied. The development of …

Experimental Boss Design And Testing, Joseph P. Mistretta

Undergraduate Honors Theses

Over the years, gaming has developed rapidly from simple pixel-based experiences to fully blown three-dimensional worlds. As developing technologies improve, so does the complexity and flexibility of what can be created. Encounters, along with all aspects of any gaming experience, have evolved along with the technologies that create them. These intense combat instances, often times referred to as “bosses”, represent a chance for the developer to challenge player skill, cooperation, and coordination. In addition to being major challenges, encounters also allow players to feel a sense of progression as they learn and adapt to mechanics incorporated within an encounter’s design. …

Characterization And Development Of Tsi Three-Dimensional Laser Doppler Velocimetry System, John Andrew Dominick

Chemical Engineering Undergraduate Honors Theses

The study of dense gas dispersion at atmospheric conditions is critical to understand the safety concerns of industrial operations where large amounts of toxic or flammable materials are stored and generated. A large airborne release of these materials into the atmosphere could have catastrophic effects. The Chemical Hazards Research Center (CHRC) at the University of Arkansas performs important research on dense gas dispersion. The CHRC houses the world’s largest ultra-low speed wind tunnel, which is used to simulate dispersion at atmospheric conditions. Substantial amounts of data, including velocities, are recorded for modeling real life gas dispersion events. Before conducting experiments, …

Separation Of Emulsified Oil From A Brackish Water Stream Using Ultrafiltration And Coalescence, Casey W. Polk

Chemical Engineering Undergraduate Honors Theses

In the past 40 years, a variety of enhanced oil recovery (EOR) methods have been developed and applied to mature, mostly depleted, and shale formation oil reservoirs. Chemical and sonic stimulation are two enhanced oil recovery methods in which emulsions are created either as a primary or secondary effect. The resulting viscosity of the oil in water emulsion is considerably lower than that of dry crude, thus increasing recovery from pay zones. During chemical enhanced oil recovery, caustic or surfactants are injected into oil reservoirs, which results in the creation of stable oil-water emulsions. The emulsions from chemical enhanced oil …

Effect Of Sodium Acetate On Butanol Production By Clostridium Saccharoperbutylacetonicum Via Abe Fermentation, Brigetta Super

Chemical Engineering Undergraduate Honors Theses

Clostridium saccharoperbutylacetonicum is used in ABE fermentation which historically produces a solvent mixture of 3:6:1 parts acetone, butanol, and ethanol respectively. The fermentation process undergoes two phases, an acidogenesis phase which produces butyric acid, and a solventogenic phase which reutilizes the butyric acid, making butanol. For ABE fermentation to compete economically with butanol production from petroleum, the concentration of butanol in the solvent product must be increased dramatically. Unpublished research by Carver student Kayla Kimbrough in the summer of 2012 showed that the addition of salts (sodium acetate) to PYG fermentation media increased butanol production from Clostridium saccharoperbutylacetonicum significantly. When …

Electrocoagulation For Sulfate Removal, Michael A. Layton

Chemical Engineering Undergraduate Honors Theses

In the United States, one of the major rising issues is water shortage, especially in Western, inland states with arid climates. Not only do deficiencies exist for potable water, but for irrigation and agricultural purposes as well. Currently, the Brackish Groundwater National Desalination Research Facility in Alamogordo, New Mexico has four separate wells that are being used for experimentation. A major concern is that a considerable amount of this water is currently wasted by being sent to evaporation ponds without any sort of treatment for human consumption. The WERC-A-HOLICS have identified two possible methods to alleviate this problem. Electrocoagulation (EC) …

Electrocoagulation For Sulfate Removal, Hailey Marie Dunsworth

Chemical Engineering Undergraduate Honors Theses

In the United States, one of the major rising issues is water shortage, especially in Western, inland states with arid climates. Not only do deficiencies exist for potable water, but for irrigation and agricultural purposes as well. Currently, the Brackish Groundwater National Desalination Research Facility in Alamogordo, New Mexico has four separate wells that are being used for experimentation. A major concern is that a considerable amount of this water can be used as another reliable source for potable water if treated. The WERC-A-HOLICS have identified two possible methods to alleviate this problem. Electrocoagulation (EC) is a technology useful for …

Radiative Cooling To The Night Sky, Alexander R. Enderlin

Chemical Engineering Undergraduate Honors Theses

Silicon wafer fabrication facilities require a significant amount of temperate cooling water to meet high internal cooling loads. The tertiary chilled water systems operate year round to fulfil the constant cooling load needed for production. Conventional chillers require a large amount of electricity to cool the water by the vapor compression cycle. As energy costs increase and environmental stewardship becomes the norm in industry, sustainable technologies are needed to chill process cooling water without the significant energy consumption of today’s chillers. Night sky radiation cools a medium by radiating heat from a warm medium to the colder night sky. The …

Impregnation And Adsorption Of Rare Earth Elements On Amberlite Xad-7, Bobby G. Hampton

Chemical Engineering Undergraduate Honors Theses

Beads were washed then impregnated with an organophosphorous extractant D2EHPA. The washing process, as well as factors in the impregnation process were studied. Water was deemed sufficient to prewash the beads before use over small and large amounts of acid with acetone. The impregnation of beads at an Amberlite D2EHPA ratio of 1:1 was determined to be best. Absorption isotherms of Neodymium were the first to be studied. By testing different concentrations, Amberlite was determined to absorb the max amount at 4000 ppm. The pH values from 2-7 were determined to have no effect on the amount of Neodymium absorbed …

Separatome Of Escherichia Coli Analysis Of Deae Chromatography As Ph Of Loading Changes, Rita E. Tejada Vaprio

Chemical Engineering Undergraduate Honors Theses

Recombinant DNA technology is used to produce therapeutics in host organisms and undergoes several purification steps before it can be used by the end user. Escherichia coli which has been widely studied has been the microorganism of choice mainly because of its low production costs. The primary objective of this study was to investigate the optimal conditions to purify a protein of interest with antifungal properties. Varying the loading pH alters the overall charge of both the target protein and host cell proteins (HCPs). Identifying genomic proteins that remain bound regardless of loading pH on DEAE columns will guide future …

Electrocoagulation For Sulfate Removal, Gina Marie Densmore

Chemical Engineering Undergraduate Honors Theses

In the United States, one of the major rising issues is water shortage, especially in Western, inland states with arid climates. Not only do deficiencies exist for potable water, but for irrigation and agricultural purposes as well. Currently, the Brackish Groundwater National Desalination Research Facility in Alamogordo, New Mexico has four separate wells that are being used for experimentation. A major concern is that a considerable amount of this water is currently wasted by being sent to evaporation ponds without any sort of treatment for human consumption. The WERC-A-HOLICS have identified two possible methods to alleviate this problem. Electrocoagulation (EC) …

Use Of Peptoid Microspheres To Improve Enzyme Linked Immunosorbent Assay (Elisa) Microarray For Early Cancer Detection, Valerie Del Carmen Reyez Loayza

Chemical Engineering Undergraduate Honors Theses

The pursuit of an efficient and economical technique for early detection of cancer has led to the development of sophisticated biosensors for antigen analysis. As biosensors become more complex, coatings are necessary and important. The preferred coatings need to have the following properties: high surface area for binding, resistance to biofouling, and flexible synthesis. The focus of this project is to determine whether using peptoid microsphere-coated glass slides in the enzyme linked immunosorbent assay (ELISA) microarray technique is better than using commercially available glass slides. Current microarray slides are coated with reactive groups, such as amines, epoxides, or aldehydes. It …

Ultrasonic Hoguanauts Werc Task 2: Separation Of Oil From Water, Jesus Eduardo Martinez

Chemical Engineering Undergraduate Honors Theses

Engineering, Chemical Engineering, Environmental

A Study Of The Influence Of Particle Gradation In Bonded Assemblies, Matthew P. Watters

Civil Engineering Undergraduate Honors Theses

The discrete element method (DEM) has been used extensively to study soil, rock, and masonry behavior because of its ability to model the materials as individual particles or bonded clumps of particles. DEM allows for examination of the macro- and micro-scale response and provides a means to study the fundamental material behavior, but it is still considered computationally expensive in relation to other methods. To lower computational costs, the smallest particle sizes are often considered negligible and are left out of the model. Additionally, rock or intact materials are often modeled as a bonded assembly of uniform spheres. To date, …

Drive Plate Mass Polar Moment Of Inertia In Stokeo Type Resonant Column Devices, Michael Ryan Deschenes

Civil Engineering Undergraduate Honors Theses

The calibration procedure employed by researchers at the University of Arkansas (UA) to calibrate two Stokoe-type resonant column torsional shear (RCTS) devices is presented herein. Specifically, the development of a device-specific calibration process to determine the mass polar moment of inertia of the RCTS drive plate assemblies (J0), as a function of frequency, is described. Three aluminum calibration specimens and three stainless steel masses with known geometric and material properties were utilized to experimentally determine the J0 values. Experimental data collected by researchers at the University of Arkansas and obtained from other sources (Utah State University, the University of Texas …

Eight Degree Of Freedom Vehicle Model With Pitch, Yaw, Tire Control And Sensor Inputs, Sean T. Hirtle

Master's Theses

This research focuses on the development of an eight degree of freedom vehicle model in the MATLAB computing language. Its purpose is to provide flexibility in the modeling and implementation of signal inputs and crash avoidance logic while maintaining accuracy in the physics of the vehicle’s motion. Firstly, the equations of motion for the bodies involved under a reasonable set of assumptions were developed. Next the model was translated to computer code. By writing the model in SimuLink with *.m files, the modularity of the code is enhanced. To validate the model, several well defined tests were simulated.

To establish …

Synthetic Aperture Radar: Rapid Detection Of Target Motion In Matlab, Daniel S. Kassen

Master's Theses

Synthetic Aperture Radar (SAR) has come into widespread use in several civilian and military applications. The focus of this paper is the military application of imaging point targets captured by an airborne SAR platform. Using the traditional SAR method of determining target motion by analyzing the difference between subsequent images takes a relatively large amount of processing resources. Using methods in this thesis, target motion can be estimated before even a single image is obtained, reducing the amount of time and power used by a significantly large amount. This thesis builds on work done by Brain Zaharri and David So. …